1. Field of the Invention
This invention relates to a translucent roof element which is designed to close an opening made in the roof of a motor vehicle.
2. Description of Related Art
It is known that the roof of a motor vehicle can be formed at least partially by a transparent or translucent pane, especially of glass or plastic material. In the known manner, the opening made in the roof is bordered by a stop which forms a contact surface and a terminating surface which is designed to hold the peripheral edge of the glass pane.
Generally, the opening extends in the transverse direction between the side roof elements of the body and in the lengthwise direction between the front roof element which separates the inside roof lining and the windshield, and the rear roof element which separates the inside roof lining and the rear window or rear hatch. The side roof elements, the front roof element and the rear roof element each have a separate peripheral stop on their edge which is located opposite the opening. The combination of these four individual peripheral stops forms the contact surface which makes it possible to hold the peripheral edge of the glass pane, permanent connection of which takes place in the known manner by cementing.
In practice, a motor vehicle with a glass roof is simply a derivative of a traditional model with a sheet metal roof. This means that the glass pane must be cemented onto a standard body, i.e., therefore, onto a contact surface which is not specifically designed for this purpose. Since at this point this contact surface in the form of a stop is designed fundamentally for welding on a sheet metal roof, it need not meet any special requirements with respect to flatness or continuity. This is a major disadvantage in the case of cementing on a glass pane.
The technique of permanent joining by cementing requires a regular, continuous contact surface which runs essentially parallel to the element which is to be permanently joined. If there are defects of flatness and/or if there are interruptions, it is such that the regularity and continuity of application of the cement are no longer ensured. This results in a major risk of leaks once the pane has been attached. If this defect is to be remedied and/or the distance between the contact surface and the surface of the element to be connected has major deviations, there can be an attempt to apply additional cement. Unfortunately, it is well known in the technical field of cementing that an excess of cement cannot be absolutely linked to good attachment.